EP4400653A1 - Deep vibrator arrangement and method for compacting the ground by means of a deep vibrator arrangement - Google Patents

Abstract

The invention relates to a deep vibrator arrangement (1) for soil compaction, comprising: a plurality of deep vibrators (2), each of which has an unbalanced mass (3) that can be driven in rotation by a rotary drive (5) in a vibrator housing (4), and at least one motion sensor (6, 12, 13, 14, 19) that is designed to detect a motion signal (P) representing the movement of the respective deep vibrator (2), and control electronics (21) to which the motion signals (P) of the deep vibrators (2) are passed on, wherein the rotary drives (5) of the deep vibrators (2) can be controlled by the control electronics (21) in such a way that the movements of the deep vibrators (2) are coordinated with one another.

Description

The invention relates to an arrangement for improving subsoil or for compacting soil, as well as a corresponding method for carrying out soil compaction.

Deep vibrators are used for deep compaction of loosely deposited soils. These are dynamically excited by a rotating imbalance and form a dynamic interaction system with the surrounding soil to be compacted. Measurements on the vibrator can be used to determine the dynamic excitation, in particular the imbalance and its position, as well as the vibrator movement, and from this the dynamic properties of the surrounding soil can be determined. Deep vibrators can be used in various methods for improving the subsoil, which are described, for example, in the applicant's brochure "The deep vibrating methods" (brochure 10-02D).

The soil is generally compacted by the dynamically activated vibrator penetrating the soil to the desired compaction depth at a compaction point, possibly with the aid of water flushing, and then either being pulled in stages and held until a termination criterion is reached, or by tamping movements in an upward-moving pilgrim step process. Surface compaction is achieved by working on many compaction points in a grid.

In dynamic compaction, the compaction device dynamically stimulates the soil and causes it to vibrate, which mobilizes the soil grains and causes them to become denser. This compaction process requires a certain amount of time during which the vibration must be maintained. This takes place, When compacting using a deep vibrator, the termination criteria are taken into account, which define the end of each individual compaction step at a depth level and initiate the next compaction step (step-by-step pulling). The range of the compaction device depends on the type of excitation (amplitude, frequency) and its geometry as well as the soil properties.

From the EN 10 2016 125 155 A1 A compaction system with several separate vibrator rods attached to a support is known. The vibrator rods can be arranged in a grid of two to ten. The operating data of the compaction system and the vibrators, such as speed, temperature and pressure, are permanently recorded using integrated sensors.

From the EP 3 517 687 B1 A method is known for compaction detection and control when compacting a soil using a deep vibrator, which has an imbalance that can be driven in rotation in a vibrator housing and several sensors. The method comprises: introducing the deep vibrator into the soil to a desired final depth; compacting the soil using the deep vibrator in compaction steps, wherein during compaction to a measured depth the lead angle of the imbalance and the vibration amplitude of the deep vibrator are determined; recording a soil stiffness curve from soil stiffness values that are determined over time on the basis of the lead angle and the vibration amplitude; determining first and second soil stiffness values for which a second rate of increase is greater than a first rate of increase of the soil stiffness value; calculating a transition soil stiffness value that lies between the first and second soil stiffness values; and storing the transition soil stiffness value recorded in each case at the associated depth. A soil stiffness profile can be created based on transitional soil stiffness values recorded over depth.

With large compaction machines, the drive motors can heat up and cannot maintain the vibration required for compaction for long enough. The criteria for stopping compaction may therefore no longer be motivated by soil mechanics, but rather depend on the capabilities of the vibrator.

The present invention is based on the object of proposing an arrangement for soil compaction or for improving a building site that enables a particularly high compaction performance. The object is also to propose a corresponding method for efficient soil compaction.

To solve this problem, a deep vibrator arrangement for soil compaction is proposed, comprising: a plurality of deep vibrators, each of which has an imbalance that can be driven in rotation by a rotary drive in a vibrator housing and at least one sensor that is designed to detect a movement signal representing the movement of the respective deep vibrator, control electronics to which the movement signals of the deep vibrators are passed on, wherein the rotary drives of the deep vibrators can be controlled by the control electronics in such a way that the movements of the deep vibrators are coordinated with one another.

One advantage of the arrangement is that the coordinated, dynamically synchronized interaction of several deep vibrators enables particularly efficient compaction, i.e. the arrangement with coordinated control of the deep vibrators is more effective than the sum of the individual components. In this way, the effect of a large device can be achieved with a number of smaller deep vibrators without having to accept its disadvantages and limitations. The number of deep vibrators can in principle be freely selected and can be adapted to the subsoil requirements. For example, the arrangement can comprise two, three, four or more deep vibrators, which are preferably arranged symmetrically. The deep vibrators can be arranged on one or more carrier devices. The distance between the vibrators in the group is an important parameter that must be coordinated with the soil to be compacted in such a way that, on the one hand, sufficient mobilization of the enclosed area and, on the other hand, the greatest possible range are achieved. Another advantage of the arrangement is that the instrumented deep vibrators can be used to carry out geomechanical tests for quality control purposes.

All deep vibrators are electronically connected to a central control electronics. To control process parameters such as frequency, unbalance, water addition, Peak pressure, etc. In order to optimize the compaction success, a control criterion can be used which is based on the caster angle of the ground reaction force and is suitable both for the individual vibrator and for the synchronized application of several deep vibrators.

In the context of the present disclosure, a synchronized movement includes in particular that the positions or movements of the vibrators remain the same or repeat regularly. This can apply to vibrators rotating in the same or opposite directions. The angular speeds of the vibrators are preferably the same. All vibrators preferably always have the same phase angle with respect to a reference direction, which is counted as positive in the direction of rotation.

According to one embodiment, a deep vibrator can have a device for dynamic excitation, a drive for generating the excitation, optionally wings for reducing the twisting during compaction, optional water outlet openings at the tip and optionally on the vibrator line, a dynamic decoupling to the vibrator line and a suspension on the carrier device. The excitation drive can comprise a motor, a rotating shaft, one or more unbalanced masses, which can optionally be equipped with a turnover weight.

According to one embodiment, the deep vibrators can each be equipped with wings. The wings can be used to influence the movement behavior of an individual vibrator and its range. If the wings of all the vibrators in a group are parallel to each other, synchronization of the vibrator movements is easier to achieve, but the compaction result is direction-dependent, which is usually undesirable. A more uniform compaction result is achieved if the wings are omitted.

According to a possible embodiment, anti-rotation means can be provided to prevent the vibrators of the group from rotating at their suspension. The use of wings to brake the rotation around the vertical axis is therefore not necessary, or their dimensions can be reduced.

The possible sensors can be selected depending on the application and requirements. In order to synchronize the movement of several vibrators, at least one motion sensor is provided on each vibrator, which detects a motion signal representing the movement of the vibrator. If the excitation is to be synchronized, the positions of the imbalances of the deep vibrators must be detected using position sensors. According to one possible embodiment, several sensors can be attached to each of the deep vibrators, which sense the movement behavior or the acceleration and/or the position of the imbalance. Several acceleration sensors can be attached to the deep vibrator at different levels. From bidirectional acceleration measurements in two levels of a vibrator, the horizontal movement behavior can be determined at any point on the vibrator, for example at the tip or the position of the imbalance excitation. By integrating these horizontal accelerations twice, the associated vibration paths can be determined, which, when halved, lead to the vibration path amplitude A. The vibrator movement lags behind the dynamic excitation caused by the rotating imbalance. By determining the position of the imbalance and comparing it with the vibrator movement, the lead angle ϕ can be determined. As far as only the synchronization of the vibrator movement is described within the scope of the present disclosure, it is understood that the laws are also applicable to the synchronization of the excitation.

If the rotation of the deep vibrators around the vertical axis is not mechanically prevented, the rotation must be measured in order to compensate for it during synchronization. Furthermore, the motor power and/or the temperature of the drive motor can optionally be recorded using corresponding power or temperature sensors. According to one embodiment, the pressures and/or flow rates for peak water, underwater water and/or headwater can also be recorded using corresponding pressure and/or flow sensors. A dynamic reaction of the soil can optionally be measured using sensors on the surface and/or in depth, whereby the deep sensors under the groundwater can also determine the pore water pressures. From the known weight of the vibrator and a measured crane load, a vertical load can be calculated if necessary. of the soil by the vibrator. If deep vibrators with blades are used, the orientation of the blades can optionally be determined by measuring the vibrator rotation, which has an influence on the vibrator movement.

The deep vibrators preferably have power reserves for synchronization. The control electronics can be designed to primarily control the rotary drive of one of the deep vibrators depending on the movement signals of the deep vibrators, and to secondarily control the rotary drive of at least one other of the deep vibrators, such that the rotary movement of the secondarily controlled rotary drive is coordinated with the rotary movement of the primarily controlled rotary drive. The control electronics are preferably designed to control the rotary movement of the secondarily controlled rotary drive synchronously with the rotary movement of the primarily controlled rotary drive, in particular with the same movement speed.

The primary deep vibrator can also be referred to as the "master", while the other deep vibrators are operated in dependent mode, which can also be referred to as "slave" operation. Any deep vibrator in the group can be selected as the "master" and operated sufficiently below its power limit. The other deep vibrators in the arrangement can be controlled in "slave" mode, with their movements (or excitation) following the movement (or excitation) of the "master". The individual deep vibrators can have an independent power supply. In the case of heterogeneous soil conditions or different vibrator characteristics, an algorithm can appoint the vibrator whose power reserves are exhausted as the "master", which the other vibrators that still have power reserves must follow or follow in terms of control technology. If you switch smoothly from one operating mode to another, the "master" vibrator can continue to run undisturbed, while the others can drop back in phase in a controlled manner, i.e. rotate a little slower, until the phase position of the new operating mode is reached and can be maintained.

With the group of at least two synchronized vibrators, it is possible to effectively work soils that would already be problematic for a single vibrator. because the area enclosed by the vibrators can be mobilized. This is possible because the arrangement is made up of flexibly correlable individual components that work together and can, for example, simulate a large vibrator that can optionally change its shape and/or volume dynamically. Depending on geotechnical and operational requirements, there are different options for synchronization, which can be assigned to different operating modes.

After a first mode of operation, the control electronics can regulate the rotary movements of several of the deep vibrators with the same direction of rotation, the same phase position and the same angular speed. This mode of operation is similar to that of a large vibrator. In this mode of operation, the vibrator movements (or excitations) are synchronized in such a way that a common parallel displacement of the entire group occurs. Self-synchronization in this mode of operation is not excluded, but is not sought because of its unreliability and the corresponding phase shifts. In terms of soil mechanics, a large range is achieved, the area enclosed by the vibrators is not subjected to maximum stress due to the lack of shear distortions. The vibration effect on the environment is considerable. Although this is irrelevant for most deep compaction construction sites, the energy used to vibrate the environment (geometric damping) is lost for soil compaction.

In a second mode of operation, the control electronics can regulate the rotary movements of at least two of the deep vibrators with the same direction of rotation, the same angular speed and phase positions offset by 180° from one another. This mode of operation can also be referred to as "oscillation and compression". The imbalances of the deep vibrators, which rotate in the same direction, are synchronized in such a way that the horizontal forces on the ground cancel each other out and a dynamic torsional moment is created globally around the vertical axis. During operation, the pattern that dynamically rotates around the vertical axis alternately clockwise and anticlockwise (oscillating) also cyclically becomes smaller and larger (compression and expansion). Outside the surrounding area, the oscillation generates shear distortions that serve to compact the material.

According to a third mode of operation, the control electronics can be designed to control the rotary movements of at least two of the deep vibrators starting from an identical phase position in a reference plane spanned by the longitudinal axes of the deep vibrators with opposite directions of rotation and the same angular speed. This mode of operation can also be referred to as a "directional vibrator with oscillation".

According to a fourth mode of operation, the control electronics can be designed to control the rotary movements of at least two of the deep vibrators, starting from an identical phase position perpendicular to a reference plane spanned by the longitudinal axes of the deep vibrators, with opposite directions of rotation and the same angular speed. This mode of operation can also be referred to as "directional vibrator with compression". When using an arrangement with four deep vibrators, the axes of which can be arranged to enclose a rectangle, the imbalances of the deep vibrators can be operated diagonally in different directions of rotation. The deep vibrators can be synchronized so that they work in "directional vibrator" mode, whereby the global direction of vibration, in which all vibrators act in phase, can be freely set. Perpendicular to this, the forces on the ground equalize each other so that only local shear distortions occur. In order to achieve a uniform range of compaction around the group, the global direction of vibration can be rotated continuously, whereby at least half a rotation (or an integer multiple thereof) should be achieved with each compaction step. The vibration of the environment and the energy lost for compaction are relatively high, similar to the "large vibrator". With a rotating direction of vibration, the vibration of the environment can be perceived as a pulsating sound.

In one embodiment, four deep vibrators arranged in a square or rectangular shape, for example, can be used, but this is not limited to them. However, it is understood that different numbers of vibrators can be used for all configurations. In an embodiment with more than two, in particular with four deep vibrators, in addition to all of the above-mentioned operating modes "large vibrator", "oscillation with compression" and "directional vibrator", alternatively or additionally modified and other operating modes can be implemented. In some operating modes the forces acting on the ground can largely be equalized. Due to the lack of a global effect on the ground, the vibration of the surrounding area can be minimized and the energy introduced is primarily available for local compaction and mobilization.

In particular, another operating mode for four deep vibrators is characterized by the fact that all vibrators are synchronized in the same direction of rotation in such a way that the vibrators on one diagonal move towards each other while the vibrators on the other diagonal move apart. This can be done alternately and cyclically by the dynamic excitation. Locally, the soil area between the vibrators is subjected to dynamic shear distortions, which is why this mode of operation can also be referred to as "shear distortion". The shear distortions lead to the mobilization and compaction of the soil in a highly effective manner.

Another operating mode for an arrangement with four vibrators is characterized by the fact that the imbalances of the deep vibrators are driven diagonally in different directions of rotation. The local impact on the ground is achieved by a combination of dynamic shear distortions, which alternate with compression and expansion movements. This operating mode can also be referred to as "shear distortion with compression".

A deep vibrator can be mounted on a carrier device, for example a cable excavator, and can be vibrated into the soil to be compacted either freely suspended or guided (leader). When the final depth is reached, the frequency and/or the eccentricity of the dynamic excitation can be changed in order to compact the soil, depending on its properties, by pulling it step by step from bottom to top or by tamping it in a pilgrim step, with material added from above or at the tip (lock vibrator) with water added at the tip (underwater) and, if necessary, on the vibrator line (upstream). Compaction can be carried out in a grid, for example triangular or square, and can be coordinated and optimized to the combination of subsoil properties - compaction device - compaction requirement. If necessary, after the first grid has been processed, an additional Grid, especially a secondary grid in the intermediate points, should be densified.

According to a procedure, the unbalance can be driven in rotation in such a way that a frequency of the rotational movement is changed over a measurement period, whereby the vibration amplitude (A) of the deep vibrator is determined during the measurement period. In particular, the frequency range is selected so that the vibrator housing and the surrounding soil are coupled to one another and vibrate over at least a portion of the frequency range. The unbalance can be driven in rotation from a standstill so that the frequency of the rotational movement is increased starting from zero over the measurement period. In particular, the frequency can be increased progressively across the frequency range. This procedure can be carried out at different depths as part of soil improvement. For this, the actual processing process is stopped and then the unbalance is driven in the manner described. This procedure can also be referred to as a "listening stop".

Determining the vibration amplitude during a change in the frequency of the rotational movement of the unbalance advantageously leads to particularly precise and reliable results, since the deep vibrator is used in a similar way to a measuring probe by running through a frequency response. The conditions for a measurement are better than when the deep vibrator is being used for compaction. The vibration amplitude is an important parameter for evaluating the compaction of the soil. The deep vibrator is not introduced into the soil exclusively for the measuring process described. The method according to the invention can advantageously be used during compaction of the soil using the deep vibrator, or can be carried out alternately with the compaction process.

erfolgen kann.According to a further procedure, a soil stiffness value (k) can be calculated based on at least the vibration amplitude (A) and optionally also taking into account the lead angle (ϕ). The lead angle (ϕ) refers to the phase angle by which the unbalance mass is offset from the measuring direction of the sensors during the vibration movement. In addition, this can be the soil stiffness of the The soil stiffness signal (k) representing the soil can also be calculated taking into account the mass (M) of the deep vibrator. Alternatively or in addition, the determination of the soil stiffness signal (k) representing the soil stiffness of the soil can be carried out taking into account a soil mass characteristic value (ΔM) representing the soil mass vibrating on the deep vibrator, in particular the modal soil mass. This soil mass characteristic value (ΔM) representing the soil mass vibrating can be calculated, for example, on the basis of the imbalance (m · e), the vibration amplitude (A) and the mass (M) of the deep vibrator, the calculation being carried out in particular at least approximately according to the formula: $$\mathit{\Delta M}=\frac{m\cdot e}{A}-M$$

can be done.

wobei M die modale Rüttlermasse, ΔM die modale mitschwingende Bodenmasse und m · e die Unwucht im Rüttler (Unwuchtmasse mal Exzentrizität) ist. Bei freier Schwingung beträgt der Vergrößerungsfaktor eins.According to a preferred method, the determination of the soil stiffness signal (k) representing the soil stiffness of the soil can also be carried out taking into account the measured amplitude (A) and a comparison amplitude (A∞). The amplitude of the vibrator at a certain excitation frequency (ω) during free vibration can be used as the comparison amplitude. In order to calculate the magnification function (V), the measured vibration path amplitude (A) can be related to the theoretical amplitude (A∞) at a theoretically infinitely high excitation frequency, i.e. $$V=\frac{A}{A_{\infty }}=\frac{A\cdot \left(M+\mathit{\Delta M}\right)}{m\cdot e}$$

where M is the modal vibrator mass, ΔM is the modal vibrating soil mass and m · e is the unbalance in the vibrator (unbalance mass times eccentricity). In the case of free vibration, the magnification factor is one.

berechnet werden, wobei

• A die Schwingungsamplitude des Tiefenrüttlers während des Verdichtens,
• A∞ die Schwingungsamplitude des Tiefenrüttlers bei freier Schwingung, beziehungsweise bei gegen unendlich laufender Erregerfrequenz,
• F die Zentrifugalkraft,
• m die Unwuchtmasse,
• e die Exzentrizität der rotierenden Unwucht m zur Drehachse,
• ω die Winkelgeschwindigkeit der rotierenden Unwucht, und
• ϕ der Phasenvorlauf der rotierenden Unwucht m zur Masse M des Tiefenrüttlers,

sind. Mit dieser Formel wird auch der dynamische Anteil der schwingungsrelevanten Größen berücksichtigt. Es versteht sich jedoch, dass grundsätzlich auch andere Berechnungsmethoden für die Berechnung eines die Steifigkeit des Bodens repräsentierenden Steifigkeitssignals möglich sind. Beispielsweise kann eine Berechnung auch gemäß der nachstehenden Formel erfolgen: $$k\approx \frac{m\cdot e\cdot {\omega }^2}{A}$$

According to a possible procedure, the determination of the soil stiffness of the soil stiffness signal (k) representing the soil at least approximately according to the formula: $$k=m\cdot e\cdot {\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega </figure-callout>}}^2\cdot \left(\frac{1}{A_{\infty }}-\frac{1}{A}\cdot \frac{\mathrm{sign}\left(\varphi -90°\right)}{\sqrt{1+{\tan }^2\varphi }}\right)$$

be calculated, where

• A is the vibration amplitude of the deep vibrator during compaction,
• A∞ is the vibration amplitude of the deep vibrator during free vibration, or when the excitation frequency is running towards infinity,
• F is the centrifugal force,
• m is the unbalance mass,
• e is the eccentricity of the rotating unbalance m to the axis of rotation,
• ω is the angular velocity of the rotating unbalance, and
• ϕ is the phase advance of the rotating unbalance m to the mass M of the deep vibrator,

This formula also takes into account the dynamic part of the vibration-relevant quantities. However, it is understood that other calculation methods are also possible for calculating a stiffness signal representing the stiffness of the ground. For example, a calculation can also be carried out according to the following formula: $$k\approx \frac{m\cdot e\cdot {\omega }^2}{A}$$

According to one possible procedure, a crosshole test can also be carried out with the deep vibrator arrangement. For this purpose, the compaction activity is briefly interrupted. Any one of the deep vibrators is operated actively, and at least some of the other deep vibrators are operated passively, with the passively operated deep vibrators using their sensors to record the signals from the active deep vibrator that they receive through the ground in between.

Figur 1

einen beispielhaften Tiefenrüttler, der für eine erfindungsgemäße Anordnung verwendbar ist;

Figur 2

eine erfindungsgemäße Tiefenrüttleranordnung zur Bodenverdichtung in einer ersten Ausführungsform mit zwei Tiefenrüttlern in Schnittdarstellung;

Figur 3A

die Tiefenrüttleranordnung gemäß Figur 2 während des Betriebs in einer ersten Betriebsweise;

Figur 3B

die Tiefenrüttleranordnung in der Betriebsweise gemäß Figur 3A nach einer Viertel Periode beziehungsweise 90° Verdrehung;

Figur 4A

die Tiefenrüttleranordnung gemäß Figur 2 während des Betriebs in einer zweiten Betriebsweise;

Figur 4B

die Tiefenrüttleranordnung in der Betriebsweise gemäß Figur 4A nach einer Viertel Periode beziehungsweise 90° Verdrehung;

Figur 5A

die Tiefenrüttleranordnung gemäß Figur 2 während des Betriebs in einer dritten Betriebsweise;

Figur 5B

die Tiefenrüttleranordnung in der Betriebsweise gemäß Figur 5A nach einer Viertel Periode beziehungsweise 90° Verdrehung;

Figur 6A

die Tiefenrüttleranordnung gemäß Figur 2 während des Betriebs in einer vierten Betriebsweise;

Figur 6B

die Tiefenrüttleranordnung in der Betriebsweise gemäß Figur 6A nach einer Viertel Periode;

Figur 7A

eine erfindungsgemäße Tiefenrüttleranordnung zur Bodenverdichtung in einer zweiten Ausführungsform mit vier Tiefenrüttlern schematisch in Draufsicht in einer ersten Betriebsweise;

Figur 7B

die Tiefenrüttleranordnung aus Figur 7A schematisch im Längsschnitt beziehungsweise Seitenansicht;

Figur 8A

zum Vergleich einen einzigen Tiefenrüttler zur Bodenverdichtung schematisch in Draufsicht;

Figur 8B

den Tiefenrüttler aus Figur 8A schematisch im Längsschnitt beziehungsweise Seitenansicht;

Figur 9A

die Tiefenrüttleranordnung gemäß Figur 7A in einer ersten Betriebsweise;

Figur 9B

die Tiefenrüttleranordnung aus Figur 9A nach einer Viertel Periode;

Figur 10A

die Tiefenrüttleranordnung gemäß Figur 7A in einer zweiten Betriebsweise;

Figur 10B

die Tiefenrüttleranordnung aus Figur 10A nach einer Viertel Periode;

Figur 11A

die Tiefenrüttleranordnung gemäß Figur 7A in einer dritten Betriebsweise;

Figur 11B

die Tiefenrüttleranordnung aus Figur 11A nach einer Viertel Periode;

Figur 12A

die Tiefenrüttleranordnung gemäß Figur 7A in einer vierten Betriebsweise;

Figur 12B

die Tiefenrüttleranordnung aus Figur 12A nach einer Viertel Periode;

Figur 13A

die Tiefenrüttleranordnung gemäß Figur 7A in einer fünften Betriebsweise;

Figur 13B

die Tiefenrüttleranordnung aus Figur 13A nach einer Viertel Periode;

Figur 14A

die Tiefenrüttleranordnung gemäß Figur 7A in einer sechsten Betriebsweise;

Figur 14B

die Tiefenrüttleranordnung aus Figur 14A nach einer Viertel Periode;

Figur 15

einen Tiefenrüttler der Tiefenrüttleranordnung gemäß Figur 2 während des Betriebs in einer weiteren Betriebsweise;

Figur 16

die Tiefenrüttleranordnung gemäß Figur 2 während des Betriebs in einer weiteren Betriebsweise;

Figur 17A

schematisch einen Schnitt durch den Rüttler in der Erregerebene im Nullversuch, frei in der Luft hängend;

Figur 17B

schematisch einen Schnitt durch den Rüttler in der Erregerebene bei der Verdichtung im Boden; und

Figur 18

schematisch den geometrischen Zusammenhang von Kraft und Auslenkung zur Bestimmung der Größe und Lage der Bodenreaktionskraft.

Preferred embodiments are explained below with reference to the drawing figures. Herein:

Figure 1

an exemplary deep vibrator that can be used for an arrangement according to the invention;

Figure 2

a deep vibrator arrangement according to the invention for soil compaction in a first embodiment with two deep vibrators in a sectional view;

Figure 3A

the deep vibrator arrangement according to Figure 2 during operation in a first operating mode;

Figure 3B

the deep vibrator arrangement in the operating mode according to Figure 3A after a quarter period or 90° rotation;

Figure 4A

the deep vibrator arrangement according to Figure 2 during operation in a second operating mode;

Figure 4B

the deep vibrator arrangement in the operating mode according to Figure 4A after a quarter period or 90° rotation;

Figure 5A

the deep vibrator arrangement according to Figure 2 during operation in a third mode of operation;

Figure 5B

the deep vibrator arrangement in the operating mode according to Figure 5A after a quarter period or 90° rotation;

Figure 6A

the deep vibrator arrangement according to Figure 2 during operation in a fourth mode of operation;

Figure 6B

the deep vibrator arrangement in the operating mode according to Figure 6A after a quarter period;

Figure 7A

a deep vibrator arrangement according to the invention for soil compaction in a second embodiment with four deep vibrators schematically in plan view in a first operating mode;

Figure 7B

the deep vibrator arrangement Figure 7A schematically in longitudinal section or side view;

Figure 8A

for comparison, a single deep vibrator for soil compaction schematically in plan view;

Figure 8B

the deep vibrator Figure 8A schematically in longitudinal section or side view;

Figure 9A

the deep vibrator arrangement according to Figure 7A in a first mode of operation;

Figure 9B

the deep vibrator arrangement Figure 9A after a quarter period;

Figure 10A

the deep vibrator arrangement according to Figure 7A in a second operating mode;

Figure 10B

the deep vibrator arrangement Figure 10A after a quarter period;

Figure 11A

the deep vibrator arrangement according to Figure 7A in a third mode of operation;

Figure 11B

the deep vibrator arrangement Figure 11A after a quarter period;

Figure 12A

the deep vibrator arrangement according to Figure 7A in a fourth mode of operation;

Figure 12B

the deep vibrator arrangement Figure 12A after a quarter period;

Figure 13A

the deep vibrator arrangement according to Figure 7A in a fifth mode of operation;

Figure 13B

the deep vibrator arrangement Figure 13A after a quarter period;

Figure 14A

the deep vibrator arrangement according to Figure 7A in a sixth mode of operation;

Figure 14B

the deep vibrator arrangement Figure 14A after a quarter period;

Figure 15

a deep vibrator of the deep vibrator arrangement according to Figure 2 during operation in another operating mode;

Figure 16

the deep vibrator arrangement according to Figure 2 during operation in another operating mode;

Figure 17A

schematically a cross-section through the vibrator in the excitation plane in the zero test, hanging freely in the air;

Figure 17B

schematically a section through the vibrator in the excitation plane during compaction in the soil; and

Figure 18

schematically the geometric relationship between force and deflection for determining the magnitude and position of the ground reaction force.

The Figures 1 and 2 are described together below. A deep vibrator 2 is used to compact soil using an unbalance. An unbalance is understood to be a rotating body 3 whose mass is not distributed rotationally symmetrically. The mass axis of inertia of the mass body 3 is offset from the axis of rotation B, so that the unbalance generates vibrations when rotating, which compact the soil and any additional material Z. The process of vibratory compaction is based on the effect that the vibration of the deep vibrator 2 temporarily eliminates the friction between the soil grains and existing pore spaces close almost to the densest position due to gravity. Depending on the nature of the soil and the amount of compaction required, a reduction in volume occurs.

A deep vibrator 2 suitable for the invention comprises as essential components the rotating mass body 3, which can be driven in rotation about the rotation axis B in a vibrator housing 4. The mass body 3 can be driven by a rotary drive 5, for example an electric motor, via a drive shaft 16. A position signal representing the position of the unbalance 3 can be detected by means of a corresponding sensor 6.

The deep vibrator 2 can be suspended from a rod 8 via an elastic coupling 7. The sinking and/or compaction can optionally be facilitated by one or more water flushes 9, 10 via lines 11 integrated in the rod 8. The water flow and/or the water pressure can be measured and then controlled using appropriate sensors 12 if necessary.

First acceleration sensors 13 can be provided in a first plane E13 of the deep vibrator 2, in particular above the unbalance 3, and second acceleration sensors 14 in a second plane E14, in particular below the unbalance 3. The acceleration sensors 13, 14 are used to measure the acceleration of the deep vibrator 2 during the vibration process. From bidirectional acceleration measurements in two planes E13, E14 of the vibrator 2, the horizontal movement behavior can be determined at any point on the vibrator, for example at the tip 15 or in the position of excitation by the unbalance 3. In particular, the vibration path at the vibrator tip 15 corresponds to twice the vibration path amplitude.

Furthermore, force sensors 19 can be provided for detecting the suspension force of the vibrator 2 or for determining the peak pressure of the vibrator. In addition, at least one sensor (not shown) can be provided for measuring the penetration depth T of the deep vibrator 2. Optionally, the deep vibrator 2 can also have wings.

Figure 2 shows an arrangement according to the invention with two deep vibrators 2, each of which has an imbalance 3 that can be driven in rotation in a vibrator housing 4 by a rotary drive 5, as well as at least one motion sensor that is designed to detect a motion signal representing the movement of the respective deep vibrator. Control electronics 21 are also provided, to which the motion signals of the deep vibrators 2 are passed on. The control electronics 21 controls the rotary drives 5 of the deep vibrators 2 in such a way that their movements are coordinated with one another. Optionally, one or both of the deep vibrators can also have any other design that is suitable in connection with Figure 1 are described.

For example, several acceleration sensors 13, 14 can be attached to the deep vibrator in different planes E13, E14. From bidirectional acceleration measurements in two planes of a vibrator, the horizontal movement behavior can be determined at any point on the vibrator, for example at the tip or the location of the imbalance excitation.

The two deep vibrators 2 are preferably operated in such a way that they have power reserves for synchronization. The deep vibrators 2 can be controlled by the control electronics 21 can be controlled, for example, in such a way that - depending on the movement signals from both deep vibrators - the rotary drive 5 of one of the two deep vibrators 2 is primarily controlled, while the rotary drive 3 of the other of the deep vibrators 2 is secondarily controlled. The rotary movement of the secondarily controlled rotary drive 5 is coordinated with the rotary movement of the primarily controlled rotary drive, in particular synchronously, which includes an equal movement speed and/or deflection of the two deep vibrators. The synchronized movement of the two deep vibrators 2 compacts the material, with the material movement U being shown with solid arrows. The material movement forms a settlement funnel. A space created by the compaction can be filled with additional material Z. The movement of an optional water flush S is shown with dashed arrows.

The primary deep vibrator 2 can also be referred to as the "master", while the other deep vibrator is operated in dependent mode, which can also be referred to as "slave" operation. The movement of the deep vibrator 2 controlled in "slave" operation follows the movement of the vibrator operated as the "master". The control electronics 21 can use an algorithm to make the vibrator whose power reserves are exhausted the "master" and control it accordingly, which the other vibrator, which still has power reserves, then follows in terms of control technology.

The control electronics 21 are designed to control the arrangement 1 of deep vibrators 2 in different operating modes.

A first mode of operation is in the Figures 3A and 3B shown, where the Figure 3B the vibrators opposite the position Figure 3A after a quarter period, i.e. with the vibrators rotated by 90°. The characteristic feature of this mode of operation is that both deep vibrators 2 are operated or controlled with the same direction of rotation R1, the same phase position P1 and the same angular speed. This mode of operation is similar to that of a large vibrator, which has a single vibrator with greater power, and can also be referred to as the "large vibrator" mode of operation. In the mode of operation shown, the vibrator movements are (or excitations) are synchronized in such a way that a common parallel displacement of the entire group occurs. The two vibrators always oscillate in the same direction. The dashed line shows the shape F1 of the displaced or distorted group arrangement. The dotted line shows the opposite shape F2 of the displaced or distorted group arrangement. The dashed arrow G represents the entire circular translational displacement of arrangement 1.

A second mode of operation is in the Figures 4A and 4B shown, where the Figure 4B the deep vibrators 2 opposite the position Figure 4A after a quarter period, i.e. with the vibrators rotated by 90°. A characteristic feature of this mode of operation is that the two deep vibrators 2 are driven or controlled with the same direction of rotation R1, the same angular speed, but with phase positions P1, P2 offset by 180° from one another. This mode of operation can also be referred to as "compression and oscillation". The unbalanced masses 3 of the deep vibrators 2, which rotate in the same direction of rotation, are synchronized in such a way that the horizontal forces on the ground largely cancel each other out and an overall dynamic torsional moment is created around the vertical axis A. During operation, the pattern that dynamically rotates around the vertical axis alternately clockwise and anticlockwise (oscillating) also cyclically alternates between smaller and larger (compression and expansion). This is shown by the dashed arrow G. Outside the surrounding area, the oscillation creates shear distortions that serve to compact the material. Here too, the form F1 of the shifted or distorted group arrangement is shown with a dashed line, and the opposite form F2 of the shifted or distorted group arrangement is shown with a dotted line. The global effect is oscillating; the local effect is compressing.

A third mode of operation is in the Figures 5A and 5B shown, where the Figure 5B the deep vibrators 2 opposite the position Figure 5A after a quarter period, i.e. with the vibrators rotated by 90°. The characteristic feature of this mode of operation is that the rotary movements of the two deep vibrators 2, starting from an identical phase position P1, in a reference plane EB spanned by the longitudinal axes B of the deep vibrators 2, with opposite directions of rotation R1, R2 and the same angular velocity. This mode of operation can also be referred to as a "directional oscillator with oscillation". The overall effect is that of a directional oscillator in the plane EB with a torsional moment about the vertical axis A, as shown with dashed arrows G1, G2.

A fourth mode of operation is in the Figures 6A and 6B shown, where the Figure 6B the deep vibrators 2 opposite the position Figure 6A after a quarter period, i.e. with the vibrators rotated by 90°. The characteristic feature of this mode of operation is that the rotary movements of the two deep vibrators 2 are controlled starting from a mutually identical phase position P1 perpendicular to a reference plane EB spanned by the longitudinal axes B of the deep vibrators 2 with opposite directions of rotation R1, R2 and the same angular velocity. The dashed line shows the shape F1 of the shifted or distorted group arrangement, while the dotted line shows the opposite shape F2 of the shifted or distorted group arrangement. Overall, the global effect of a directional vibrator with a locally compressing effect results. The global effect as a directional vibrator, which results in the plane ES, is shown with the dashed arrow G.

In the Figures 7A, 7B 8A, 8B show the comparison between a large single vibrator 102 and an arrangement 1 of deep vibrators 2 in plan view and side view, respectively.

For single vibrators according to the Figures 8A, 8B it can be seen that the movement of the peak water S in the annular gap to the compacted soil is opposite to the material transport in the settlement funnel U in the direction of the vibrator tip 15 and thus inhibits it. The direction of movement of the peak water S is shown with dashed arrows; that of the material with solid arrows. This prevents a continuous supply of material to the vibrator tip 15, the location of the soil compaction.

In the Figures 7A and 7B the conditions in the vibrator arrangement 1 according to the invention are shown. By jointly processing the enclosed area the material there is mobilized and can flow continuously laterally to the vibrator tip 15 in order to ensure sufficient supplies there. If the group is seen working together, a downward flowing material transport takes place in the area 23 between the vibrators, which is shown by the arrows with a solid line.

In the Figures 9 to 14 a vibrator arrangement 1 according to the invention is shown in a second embodiment with four deep vibrators 2. The structure and functioning of this embodiment largely corresponds to those according to the Figures 2 to 7 , so that with regard to the similarities, reference is made to the above description. The same or corresponding details are provided with the same reference numerals as in the Figures 2 to 7 .

Even in the Figures 9 to 14 The arrangements shown 1 can be operated or controlled in different operating modes.

The one in the Figures 9A and 9B The operating mode shown for four vibrators corresponds to the one shown in the Figures 3A and 3B shown operating mode for two vibrators. In Figure 9B the vibrators are opposite the position from Figure 9A after a quarter period, i.e. rotated by 90°. The four deep vibrators 2 are operated or controlled with the same direction of rotation R1, the same phase position P1 and the same angular speed. In this mode of operation, the vibrator movements (or excitations) are synchronized in such a way that a common parallel displacement of the entire group of vibrators occurs ("large vibrators"). The resulting global circular translation displacement is shown with arrows G.

In the Figures 10A and 10B another operating mode for an arrangement 1 with four deep vibrators 2 is shown. In Figure 10B the vibrators are opposite the position from Figure 10A after a quarter period, i.e. rotated by 90°. The characteristic feature of this mode of operation is that all vibrators are synchronized in the same direction of rotation R1 in such a way that the vibrators of one diagonal D1 move towards each other, while the vibrators of the other diagonal D2 move apart. This happens alternately and cyclically through the dynamic excitation. Lo"al the ground area between the vibrators is subjected to dynamic shear distortions, as the dashed or dotted lines show. This mode of operation can therefore also be referred to as "shear distortion". The shear distortions lead to mobilization and compaction in a highly effective manner. Globally, the horizontal forces of the vibrators on the ground equalize each other, which is why a smaller range is possible compared to the "large vibrator" mode of operation according to the Figures 9A and 9B is given. The vibration of the environment is minimized, the energy used is available for concentrated local soil compaction and mobilization. For soils where the inherent compaction potential is difficult to mobilize (light cementing, long lying time, or apparent cohesion), the "shear distortion" operating mode is therefore particularly suitable. This operating mode may also be suitable for penetration where extensive compaction is not yet desired.

In the Figures 11A and 11B another operating mode for an arrangement 1 with four deep vibrators 2 is shown. In Figure 11B the vibrators are opposite the position from Figure 11A after a quarter period, i.e. rotated by 90°. The characteristic feature of this mode of operation is that all deep vibrators 2 are driven in the same direction of rotation R1, whereby the unbalanced masses 3 of the deep vibrators are synchronized by the control electronics 21 in such a way that the horizontal forces on the ground largely equalize each other and a dynamic torsional moment is created globally around the vertical axis, which can be seen from the dashed arrows G. The deformed shapes F1, F2, which are shown as dashed and dotted lines, always represent squares. This shows that no shear distortions are effective in the enclosed area, but that the square that dynamically rotates around the vertical axis alternately clockwise and anticlockwise (oscillating) also cyclically becomes smaller and larger (compression and expansion). In this respect, this mode of operation can also be referred to as "oscillation with compression". Outside the enclosed area, the oscillation generates shear distortions that serve to compress the material. The vibration of the environment is no longer as low as in the "shear distortion" mode ( Figures 10A, 10B ), but significantly below that in operation as a large vibrator" (Figures 9A, 9B).

All operating modes with unbalanced masses running in a uniform direction of rotation (Figures 9 to 11) can be smoothly transferred into one another without interrupting operation, so that during operation it is possible to switch between the operating modes "large vibrator", "thrust distortion" and "oscillation with compression". The same applies to diagonally different directions of rotation (Figures 12 to 14). All operating modes can also be operated in the opposite direction of rotation, so that when using vibrators with turnover weights it is possible to choose between two different eccentricities of the excitation.

In the Figures 12A and 12B another operating mode for an arrangement 1 with four deep vibrators 2 is shown. In Figure 12B the vibrators are opposite the position from Figure 12A after a quarter period, i.e. rotated by 90°. A characteristic feature of this mode of operation is that the unbalanced masses 3 of the deep vibrators 2 are operated diagonally (D1, D2) in different directions of rotation R1, R2. The unbalanced masses 3 can be synchronized using the control electronics 21 so that they work in the "directional vibrator" mode, whereby the global direction of vibration, in which all vibrators act in phase, can be freely set. The forces on the ground equalize each other transversely, so that only local shear distortions ( Figure 12B ). In order to achieve a uniform range of compression around the group, the global direction of oscillation can be continuously rotated, whereby at least half a revolution (or an integer multiple thereof) should be achieved in each compression step. This mode of operation can also be referred to as a "directional oscillator with compression". The global oscillation movement is shown as a dashed arrow G.

In the Figures 13A and 13B another operating mode for an arrangement 1 with four deep vibrators 2 is shown. In Figure 13B the vibrators are opposite the position from Figure 13A after a quarter period, i.e. rotated by 90°. The characteristic feature of this mode of operation is that the unbalanced masses 3 of the deep vibrators 2 are operated diagonally (D1, D2) in different directions of rotation R1, R2 in such a way that the forces on the ground are locally equalized, thereby causing local shear distortions, and only a residual global torsional moment (dynamic oscillation moment around the vertical axis) remains. The shear deformations are maximized over a large area in this mode of operation, as both the local shear distortions and the global oscillation movement are caused. For soils that can be optimally compacted or mobilized using dynamic shear deformations, the "oscillation with shear distortion" mode of operation is ideal. The global torsional movement is shown by dashed arrows G.

In the Figures 14A and 14B another operating mode for an arrangement 1 with four deep vibrators 2 is shown. In Figure 14B the vibrators are opposite the position from Figure 14A after a quarter period, i.e. rotated by 90°. A characteristic feature of this mode of operation is that the unbalanced masses 3 of the deep vibrators 2 are driven diagonally (D1, D2) in different directions of rotation R1, R2. The forces on the ground largely or completely cancel each other out, so that the lack of global effect on the ground minimizes the vibration of the surroundings and the energy introduced is primarily available for local compaction and mobilization. This occurs through a combination of dynamic shear distortions, which alternate with compression and expansion movements. This mode of operation can also be referred to as "shear distortion with compression".

All operating modes with diagonally rotating unbalances ( Figures 12 to 14 ) can be smoothly transferred into one another without interrupting operation, so that during operation it is possible to switch between the operating modes "directional oscillator", "oscillation with shear distortion" and "shear distortion with compression". All operating modes can also be operated in the opposite direction of rotation, so that when using vibrators with a turnover weight, a choice can be made between two different eccentricities of the excitation, whereby the diagonally different direction of rotation R1, R2 must be taken into account in the design of the turnover unbalance if the mixing of small and large eccentricities is to be avoided.

With the synchronized operation of vibrator groups, numerous options are available to react flexibly to the subsoil properties and to optimally perform the compaction task under the given boundary conditions. When using deep vibrators 2 with a turnover weight, the operating modes with a uniform direction of rotation "large vibrator", "thrust distortion" and "oscillation with compression" are to be preferred if one does not want to use different vibrators diagonally or mix large and small eccentricities.

The arrangement 1 according to the invention also allows the use of the sensors for geotechnical measurements.

A geotechnical measurement, also referred to as a "listening stop", is shown schematically in Figure 15 shown. During the compaction process, a partial decoupling of the deep vibrator 2 and the soil occurs in the contact zone, so that the amplitudes A measured on the vibrators are different from those vibration amplitudes that occur in the compacted soil (in the contact area). Therefore, during penetration or during compaction, only a state-dependent soil reaction can be determined using the formulas given above. In order to create clear conditions in this regard, it is possible to interrupt the process both during penetration into the soil and during the subsequent compaction process at defined depth levels T (either with full vertical peak load or held by the carrier device) and to let the unbalance 3 run at a low angular frequency ω. The dynamic excitation is initially not sufficient to cause penetration or compaction, the deep vibrator 2 is stuck in the soil and the amplitudes A measured on the vibrator match the vibration amplitudes of the soil in the contact area.

The state-dependent reaction stiffness k can be calculated using the following approximate formula: $$k\approx \left(m\cdot e\cdot {\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega </figure-callout>}}^2\right)/A$$

The excitation frequency ω can be gradually increased in a sliding frequency response so that the measured, initially constant soil stiffness conditions begin to change significantly at the moment when the vibrator starts to act as a compaction device again.

The test can be carried out in the case of handling weights with a large or small eccentricity (m · e) and can be carried out with a single vibrator or the vibrator arrangement 1 can be used as a unit. In the latter case, synchronization, preferably in the "large vibrator" operating mode, must be carried out via the position of the unbalance, since the initially minimal vibrator movements are not suitable for synchronization.

Another geotechnical measurement is shown schematically in Figure 16 which can also be referred to as a "crosshole" test. When carrying out the "crosshole" test, several of the deep vibrators 2 are located at the same depth level T in the ground. The compaction activity is interrupted for a short time and any vibrator becomes the "active vibrator" ( Figure 16 , left vibrator). The remaining vibrators 2' ( Figure 16 , right vibrator and possibly other vibrators outside the plane of the drawing) behave passively and use their sensors to register the signals from the active vibrator, which they reach through the ground in between. To increase the measurement accuracy, the test can often be carried out with the "active vibrator" being changed in turn.

Due to the fixed or known distance A of the holding points and the inclination N of the deep vibrators 2 known by the sensors, the distances W between the vibrators are also known at depth T.

wobei v_p die Fortpflanzungsgeschwindigkeit der Kompressionswelle und v_s jene der Scherwelle, E_s der Steifemodul des Bodens, G dessen Schubmodul sowie ρ dessen Dichte sind.If signals (vibrations) are emitted to the ground by the active vibrator, they travel through the ground over the known distances W to the passive vibrators. The signals can be homogeneous (rotating imbalance) or pulse-shaped (e.g. reversal of the imbalance). The propagation speeds of the different types of waves in the ground between the vibrators are known from the travel times of the different types of waves and the known distances. The ground stiffnesses can be calculated for the compression wave (P-wave) and the shear wave (S-wave) using the following formulas: $$v_p=\sqrt{E_s/\rho }{v}_s=\sqrt{G/\rho }$$

where v _p is the propagation speed of the compression wave and v _s is the Shear wave, E _{s is} the stiffness modulus of the soil, G is its shear modulus and ρ is its density.

The stiffness modulus E _s and the shear modulus G are suitable for describing the soil stiffness, which increases significantly during compaction. Below the groundwater, the shear modulus is more meaningful, since the propagation speed of the compression wave is significantly influenced by the water content.

In the Figures 17A and 17B Furthermore, the geometric relationship for controlling the process parameters during compaction is shown.

The control of the process parameters (frequency, unbalance, water addition, peak pressure, etc.) in order to optimize the compaction success can be carried out with a control criterion which is based on the caster angle of the ground reaction force and is suitable both for the individual vibrator and for the synchronized application of several deep vibrators.

The regulation is based on the following consideration: If the deep vibrator 2 oscillates in the air ("zero test"), as in Figure 17A As shown, only the centrifugal force of the unbalance and no external forces act on the vibrator and the movement corresponds to the rotation around the common center of gravity (of the unbalance and vibrator), which is why the deflection of the vibrator is exactly in the opposite direction to the position of the unbalance (lead angle of the excitation force ϕ = 180°). The size of the deflection in the zero test ( A _∞ ) can be measured and is required for further evaluation. When compacting the soil, as in Figure 17B As shown, the measured deflection has a different magnitude ( A ) and direction ( ϕ ) in relation to the centrifugal force ( F _e ) of the unbalance. The reason for this is the forces transmitted to the ground, which can be summarized to form an oppositely directed resulting ground reaction force ( F _b ) on the vibrator.

The magnitude and direction of the resulting ground reaction force ( F _b ) can be calculated as follows using Figure 18 described.

Figure 18 shows the geometric relationship of the vector addition for the forces and the associated deflections for the case with one degree of freedom. This case occurs when the ground reaction force acts on a balanced vibrator approximately in the plane of excitation, which is usually the case in practice. The ground reaction force (magnitude and direction) required to cause the deflection (magnitude and direction) measured during soil compaction is determined. From this geometric relationship, the ground reaction force ( F _b ) related to the excitation force (F _e ) can be determined using the following formula: $$\frac{F_b}{F_e}=\sqrt{{\left[\mathit{sin}\left(180°-\mathrm{<figure-callout\; id="2"\; label="\phi "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\varphi </figure-callout>}\right)\right]}^2+{\left[\mathit{cos}\left(180°-\varphi \right)-\frac{A}{A_{\infty }}\right]}^2}$$

The caster angle of the ground reaction force ( ϕ _b,eff ) on the vibrator is: $${\varphi }_{b,\mathit{eff}}=90°-\mathit{atan}\left[\frac{\mathit{cos}\left(180°-\varphi \right)-\frac{A}{A_{\infty }}}{\mathit{sin}\left(180°-\varphi \right)}\right]$$

Since the force acts in the opposite direction on the ground, the lead angle of the excitation force ( ϕ _b,err ) on the ground is: $${\varphi }_{b,\mathit{err}}=180°-{\varphi }_{b,\mathit{eff}}$$

According to the invention, this value is used to regulate the process parameters (frequency, unbalance, water addition, peak pressure, etc.) and should theoretically assume the value 90° when the natural frequency of the ground reaction force is reached. However, due to soil mechanical phenomena in the contact area between the vibrator and the ground (fluidized zone, vertically flowing soil material, etc.), the target value of the control for optimal soil compaction can deviate from the theoretical value of 90°. The aim of the control is to carry out soil compaction at the natural frequency of the ground reaction force by utilizing the available engine power, the available unbalance eccentricities and the appropriate frequency and water addition in order to optimize the range and compaction success.

The inventive method of soil compaction in the natural frequency of the ground contact force ( ϕ _b,err ≈ 90°) was shown above as an example for one degree of freedom, but it is not limited to one degree of freedom, but can be extended accordingly.

A deep vibrator 2 is particularly well-adjusted when it is dynamically excited while hanging freely in the air (zero test) and its resting point is located at the joint to the vibrator string. No significant vibrations are transferred to the vibrator string and vice versa, no significant dynamic forces are transferred from the string to the vibrator.

The deep vibrator 2 is particularly well-balanced as a compaction device when the resulting dynamic ground reaction force acts in the plane of the excitation during compaction and the pole is therefore still located at the joint. The vibration forms of the vibrator are then identical during the zero test (hanging freely in the air) and during compaction, only the amplitude and phase angle are different, since compaction work is carried out in the ground.

List of reference symbols

1

arrangement

2

Deep vibrator

3

Mass body

4

Vibrator housing

5

Rotary drive

6

Sensor / angle encoder

7

coupling

8th

Rods

9

Water flush

10

Water flush

11

Line

12

Sensor / water pressure sensor, water flow meter

13

Sensor / Accelerometer

14

Sensor / Accelerometer

15

Great

16

drive shaft

17

Floor

19

Force sensor

21

Control electronics

22

wing

23

Intermediate area

A

amplitude

A∞

Amplitude at infinitely high excitation frequency

B

Rotation axis

D

diagonal

e

Eccentric of the unbalance

E

level

F

shape

k

Soil stiffness index

k'

Soil stiffness increase rate

m

Mass of unbalance

M

modal vibrating mass

ΔM

modal resonating soil mass

P

Direction of movement

R

Direction of rotation

S

Water

t

Time

T

depth

U

Material movement

W

signal

Z

Additional material

β

Frequency ratio

ϕ

Lead angle

ω

Excitation frequency

Claims (14)

Deep vibrator arrangement (1) for soil compaction comprising: a plurality of deep vibrators (2), each of which has an unbalanced mass (3) which can be driven in rotation by a rotary drive (5) in a vibrator housing (4) and at least one motion sensor (6, 12, 13, 14, 19) which is designed to detect a motion signal (P) representing the movement of the respective deep vibrator (2), a control electronics (21) to which the movement signals (P) of the deep vibrators (2) are transmitted, characterized, that the rotary drives (5) of the deep vibrators (2) can be controlled by the control electronics (21) in such a way that the movements of the deep vibrators (2) are coordinated with one another. Deep vibrator arrangement according to claim 1,
characterized,
that the control electronics (21) are designed to primarily control the rotary drive (5) of one of the deep vibrators (2) depending on the rotary signals of the deep vibrators (2), and to secondarily control the rotary drive (5) of at least one other of the deep vibrators (2), such that the rotary movement of the secondarily controlled rotary drive (5) is cooperatively coordinated with the rotary movement of the primarily controlled rotary drive (5). Deep vibrator arrangement according to claim 2,
characterized,
that the control electronics (21) are designed to change the primary controlled deep vibrator (2) depending on the rotation signals of the deep vibrators (2), such that a deep vibrator (2) with lower power reserves is operated as the primary deep vibrator (2) and at least one deep vibrator (2) with larger power reserves is operated as the secondary deep vibrator (2). Deep vibrator arrangement according to claim 1 or 2,
characterized,
that the control electronics (21) are designed to control the rotary movement of the secondarily controlled rotary drive (5) synchronously with the rotary movement of the primarily controlled rotary drive (5), in particular with the same movement speed. Deep vibrator arrangement according to one of claims 1 to 3,
characterized,
that the control electronics (21) are designed to control the rotational movements of several of the deep vibrators (2) with the same direction of rotation (R1), the same phase position (P1), and the same angular velocity. Deep vibrator arrangement according to one of claims 1 to 4,
characterized,
that the control electronics (21) are designed to control the rotary movements of several of the deep vibrators (2) with the same direction of rotation (R), the same angular velocity and phase positions (P) offset by 180° from one another of at least two of the deep vibrators (2). Deep vibrator arrangement according to one of claims 1 to 6,
characterized,
that the control electronics (21) are designed to control the rotary movements of at least two of the deep vibrators (2) starting from an equal phase position (P) in a reference plane (E) spanned by the longitudinal axes (B) of the deep vibrators (2) with opposite directions of rotation (R) and the same angular velocity. Deep vibrator arrangement according to one of claims 1 to 7,
characterized,
that the control electronics (21) are designed to control the rotary movements of at least two of the deep vibrators (2) starting from an identical phase position (P) perpendicular to a reference plane (E) spanned by the longitudinal axes (B) of the deep vibrators (2) with opposite directions of rotation (R) and the same angular velocity. Method for soil compaction by means of a vibrator arrangement (1) comprising a plurality of deep vibrators (2), each of which has an unbalanced mass (3) which can be driven in rotation by a rotary drive (5) in a vibrator housing (4) and at least one sensor (6, 12, 13, 14, 19), wherein: the vibrator arrangement (1) is introduced into the ground (17) to a desired final depth (Tm) of the deep vibrators (2); the soil (17) is compacted in compaction steps by means of the vibrator arrangement (1), wherein during compaction movement signals (P) representing the rotary movements of the deep vibrators (2) are recorded by means of the sensors (6, 12, 13, 14, 19) and passed on to a control electronics (21), wherein the rotary drives (5) of the deep vibrators (2) are controlled by the control electronics (21) such that the rotary movements of the deep vibrators (2) are coordinated with one another. Method according to claim 9,
characterized,
that the rotary drive (5) of one of the deep vibrators (2) of the vibrator arrangement (1) is primarily controlled depending on the rotary signals of the deep vibrators (2), and the rotary drive (5) of at least one other of the deep vibrators (2) is secondarily controlled, wherein the rotary movement of the secondarily controlled rotary drive (5) is coordinated with the rotary movement of the primary controlled rotary drive (5). Method according to one of claims 9 or 10,
characterized,
that the unbalance (3) is driven in rotation in such a way that a frequency of the rotational movement is changed over a measuring period, wherein the vibration amplitude (A) of the deep vibrator (2) is determined during the measuring period, wherein the frequency range is selected in particular such that the vibrator housing (4) and the surrounding ground (17) are coupled to one another and set into vibration at least over a partial range of the frequency range. Method according to one of claims 9 to 11,
characterized, that the lead angle (ϕ) of the unbalance (3) and the vibration amplitude (A) of the deep vibrator (2) are determined; and that a soil stiffness value (k) is determined at least on the basis of the lead angle (ϕ) and the vibration amplitude (A); Method according to claim 12,
characterized, that the determination of the soil stiffness value (k) can be at least approximately carried out according to the formula: $$k=m\cdot e\cdot {\omega }^2\cdot \left(\frac{1}{A_{\infty }}-\frac{1}{A}\cdot \frac{\mathrm{sign}\left(\varphi -90°\right)}{\sqrt{1+{\tan }^2\varphi }}\right)$$

or: $$k\approx \frac{m\cdot e\cdot {\omega }^2}{A}$$

takes place, whereby - A is the vibration amplitude of the deep vibrator, - Ace is a comparison amplitude of the deep vibrator during free vibration, - m is a mass of the unbalance, - e an eccentricity of the rotating unbalance to a rotation axis, - ω is an angular frequency of the rotating unbalance, and - ϕ is the phase advance of the rotating unbalance to the movement of the deep vibrator, are. Method according to one of claims 9 or 10,
characterized, that compaction activity is interrupted for a short time, and one of the deep vibrators (2) is actively operated, and at least a portion of the other deep vibrators (2) are passively operated, such that they use their sensors to detect the signals of the active deep vibrator (2) which they reach through the ground in between.

Images